NeurometPlus

Incidence

Listed in OMIM in the autosomal dominant catalog. Both familial and sporadic cases have been reported. Most cases sporadic.

Clinical Characteristics

Hypomelanosis of Ito (HI) is a rare disorder that is distinguished by a lack of skin color (hypopigmentation) affecting many areas of the body. The defect in skin color is likely to appear as streaks, patches, or whorls. It is often associated with other symptoms such as intellectual and developmental retardation, seizures (neurological anomalies), ocular, skeletal and dental problems and/or a small head. The diagnosis is sometimes difficult due to the number and variety of other conditions that may be present and confuse the situation. Most cases of HI are not the result of an inherited defect, although some cases are inherited as an autosomal dominant trait. The hallmark of hypomelanosis of Ito or incontinentia pigmenti acromians is the presence of a well-defined area of hypopigmented skin along the lines of Blaschko. The hypopigmented areas may involve any body parts (large or small, linear, vorticose, or square). Wood lamp examination may be needed to demonstrate the hypopigmented areas. The skin histopathological findings are similar to those encountered in tuberous sclerosis. Hypomelanosis of Ito may be associated with nervous system, ocular, musculoskeletal, and vascular abnormalities. The most frequent neurological problems in the neonatal period are seizures and hypotonia, but arthrogryposis may also occur. Magnetic resonance imaging of the brain may reveal hydrocepahlus or atrophy. Hypomelanosis of Ito appears to be an etiologically hetereogenous physical finding. Karyotyping of the affected skin is indicated because of the possibility of chromosomal mosaicism. Hypomelanosis of Ito, also called incontinentia pigmenti achromians, is a very rare dermatosis characterized by unilateral or bilateral macular hypopigmented whorls streaks and patches. Familial cases and associations with neurological and ocular disturbances have been described. In summary it is a neurocutaneous syndrome characterized by a bizarre, more or less symmetrical leukoderma with depigmented streaks, patches, and whorls, sometimes associated with hyperkeratosis follicularis. Associated disorders include seizures, psychomotor retardation, macrocephaly, and ophthalmological and other abnormalities. Although some features are similar to those of classic incontinentia pigmenti, the differences are sufficient to establish it as a separate disorder. The disorder is characterized by unilateral or bilateral macular hypopigmented whorls, streaks, and patches which are described as the 'negative pattern' of the hyperpigmented lesions of incontinentia pigmenti. Abnormalities of the eyes and the musculoskeletal and central nervous systems occur in some. Neurologic impairment can be quite severe with hemimegalencephaly and/or migration disorders. Seventy percent of cases have associated anomalies.

Precipitants

none

Provocation Tests

none

Diagnostic Procedures

Basically it is a clinical diagnosis. Karyotyping of the affected skin is indicated because of the possibility of chromosomal mosaicism. Chromosomal mosaicism in fibroblast and/or peripheral lymphocytes shows no consistent karyotypic finding. A nonspecific marker of somatic mosaicism. The skin histopathological findings are similar to those encountered in tuberous sclerosis.